Electric and hybrid electric vehicles, such as locomotives, operate with on-board rechargeable electrical energy storage devices. The energy storage devices may include one or more types of batteries, super-capacitors, and flywheel systems.
During operation, the energy storage devices experience frequent cycles of periodic charging and discharging. Further, the operating life and performance characteristics of such devices can be affected by the rate and depth of charging/discharging and/or the current level at which the power transfer occurs. Related changes in the device's state of charge and temperature can also affect its life and performance characteristics. For example, use of faster and deeper rates of power transfer and higher current (and/or voltage) levels during bulk charging/discharging events can adversely affect the operating life and storage capacity of an energy storage device. The age of the device, frequency of usage, state of energy storage, and temperature of storage are some additional parameters affecting its performance. Reduced performance of electrical energy storage devices in turn may affect the fuel efficiency of the vehicle system in which they are used.